The Monkey Cave. Remember that in this territory there are three things of utmost importance:
<ol>
 <li>A Skip Sandwich</li>
 <li>A Picnic Lunch</li>
 <li>A Pencil Eraser</li>
</ol>
If you have these, you are prepared.
<br /><br />
Once you retrieve the almighty Trout Yogurt Machine, burn rubber back to Fourside and fight your way through the Monotoli Building to save Paula.
<br /><br />
Hop a ride back to Threed, fly to Winters on the Sky Runner, and save when you get to the lab.